1. Field of the Invention
The present invention relates to digital image signal processing, and, in particular, to computer-implemented processes, apparatuses, and systems for color converting digital image signals.
2. Description of the Related Art
Conventional systems for displaying video images in a PC environment are limited, in part, by the processing capabilities of the PC processors. These limitations include low video frame rates and small video window sizes for display of video images. Such limitations result in low video quality. As a result, some conventional systems for playing video in a PC environment require additional hardware that is designed to process video signals at the rates needed to provide acceptable video quality.
It is desirable to provide a video decoding system for displaying high-quality, full-motion digital video images on a graphics display monitor in a personal computer (PC) environment that does not require any additional hardware. Such a decoding system is preferably capable of performing decoding, conversion, and display functions to support a video playback mode. In playback mode, the decoding system accesses encoded video signals from a mass storage device, decodes the signals into a multi-component (e.g., subsampled three-component YUV9) video format, converts the multi-component signals to single-index color lookup table (CLUT) signals, and uses the CLUT signals to generate displays for a display monitor.
It is also desirable to provide a video encoding system for generating the encoded video signals that will be decoded and displayed by the video decoding system. Such an encoding system is preferably capable of performing capture, encoding, decoding, conversion, and display functions to support both a compression mode and the playback mode. In compression mode, the encoding system captures and encodes video images generated by a video generator, such as a video camera, VCR, or laser disc player. The encoded video signals may then be stored to a mass storage device, such as a hard drive or, ultimately, a CD-ROM. At the same time, the encoded video signals may also be decoded, converted, and displayed on a display monitor to monitor the compression-mode processing.
Conventional means for converting three-component video signals to single-index CLUT signals in video processing (i.e., encoding or decoding or both) systems typically define some or all of the palette colors of the finite CLUT that is used to display the video images. There are, however, computer application programs (for use in PC-based video processing systems) that also define the CLUT palette. What is needed is color conversion means for converting three-component video signals to single-index CLUT signals in a video processing system, where the color conversion means uses an arbitrary pre-defined CLUT palette, such as the CLUT palette defined by a computer application program running on the video processing system.
It is accordingly an object of this invention to overcome the disadvantages and drawbacks of the conventional art and to provide a video decoding system for displaying high-quality, full-motion video images in a PC environment.
It is a further object of this invention to provide a video encoding system for generating the encoded video signals to be decoded, converted, and displayed by the video decoding system.
It is a particular object of the present invention to provide efficient color conversion of three-component image signals to single-index CLUT signals for use in generating displays on a display monitor.
It is a further particular object of the present invention to provide means for converting three-component video signals to single-index CLUT signals using an arbitrary pre-defined CLUT palette.
Further objects and advantages of this invention will become apparent from the detailed description of a preferred embodiment which follows.